1. Field of the Invention
The present invention relates to a vehicle that drives a wheel by an electric motor.
2. Description of the Related Art
Japanese Patent Application Publication No. 2004-243921 discloses an electrically assisted vehicle. The electrically assisted vehicle includes a human power drive system that supplies a pedal force applied to pedals to a rear wheel, an assist power drive system that supplies an assist force from an electric motor to a front wheel, and a controller that controls an assist ratio which is a ratio of the assist force with respect to the pedal force. The controller reduces the assist ratio if the occurrence of a slip of the front wheel is detected, and returns the assist ratio to its original ratio if an elimination of the slip is detected. More specifically, if a slip is detected, the controller immediately lowers the assist ratio to 5%, and then gradually increases the assist ratio to its original value.